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Ride Report and PWK Carb Update

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Some history first. I previously had a friends 230F in my possession to uncork and tune. I used his bike as a reference to test my modded 230F against. My 230F has Fox shock, 150R forks, BBR 67mm piston, ST2.0 cam, head work by Terry, OE Outlaw exhaust, procom box, 13/47 gears.  After much back to back testing between these two bikes, I was really disappointed in engine performance of my modded bike. Mine was faster, but only slightly. Suspension, no comparison between stock of course.  So I ordered a OKO PWK and installed it using some rubber adapters from Home Depot. After a few needle and jet changes, I found a good setting that works very well almost everywhere, only a small flat spot at about 3/8 throttle. 

We had a ride yesterday and I was able to compare my NEW bike to my friends uncorked 230F as before. When I unloaded my bike and cranked it, he was amazed at how different it sounded and did not believe I had only added the PWK. I am happy to report that my modded bike performs as I was expecting, no comparison between the two bikes. It runs fantastic from bottom to top with a strong off idle pull and it really screams from 1/2 to WFO. I didn't think a 2 valve bike could work so well.

i think the learning is these bikes respond very very well to the basic uncorking, the most bang for the buck since it is free.  Even after adding 10cc's, more compression, a better cam, better exhaust, head porting, my bike was only slightly better than the free uncorking I did on my friends bike. But, after the PWK, WOW! 

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I tried lots of options but ended up staying with the original setup from OKO. I did spend an extra $80 to get the 2.0 slide and needle as specified by all the other PWK users. I could not get it to tune correctly and ended up going back to the original setup. The flat spot is only present initially during warm-up, it goes away after the engine is hot. I would say that it is 90% dialed in and probably 90% better than the PD. I am very happy with this setup.

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So you are saying that the OKO carb is a good PWK carburetor. I was waiting on someone to try and review them. 

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I purchased the OKO PWK clone from Mid-Atlantic. They were very helpful. I bought the delux kit that came with extra needles and jets, a clear fuel bowl, and a throttle cable kit. I also bought the 2.0 slide from jets r us that I assumed I needed to make this work. It actually tuned in very well with the OKO slide and needle and I didn't need the jets r us parts. The OKO unit is a very nice piece and I got lucky that I found a winning combination. Completely set up and running better than ever, for about $150 including carb, adapters, cable. 

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You may consider this mod which alows you to remove both jets without pulling the bowl. It does not take as much as it would seem. Start very little at a time with a chain saw file. It takes half what it looks like. However, since the seal is with the outer o ring, you can afford to take to much. However you need metal to support the oring. 

20170514_083633.jpg

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On 8/8/2017 at 7:58 PM, ROD Kerry said:

So you are saying that the OKO carb is a good PWK carburetor. I was waiting on someone to try and review them. 

I have compared them side by side. Interchanged parts, etc. They seem exactly the same to me with the exception of the slide finish. Both use Kelign inner parts. The OKO does come with an air screw with an oring. The oring is better  to stabilize the air screw. I think they are basically GMC/Chevy

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On 8/8/2017 at 5:51 PM, jeffrow68 said:

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 It actually tuned in very well with the OKO slide and needle and I didn't need the jets r us parts. The OKO unit is a very nice piece and I got lucky that I found a winning combination. Completely set up and running better than ever, for about $150 including carb, adapters, cable. 

What is your jetting and any mods to the engine?

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Chuck, this is a post from another thread when I first installed the OKO. Jetting and needle info is listed below. I think I got lucky with this combo, as I did eventually test the 2.0 slide and needle but couldn't get it to tune. 

I have some good news to report today.  To recap, I have a slightly modded 230F with the BBR 67mm piston, ST2.0 cam, ported head, EO full exhaust, but was running the OEM carb and having less than stellar results when I compared this bike to a stock uncorked bike. I figured the carb was the hold back and I think I was correct in this assumption. 

I ordered the OKO 28mm PWK from Mid-Atlantic Trials to try as a low cost test on my 230.  I got the carb, angled cable top, clear fuel bowl, and a build your own cable with additional jets and needles.  I also ordered the 2.0 slide and JJL needle from jetsrus.  The 2.0'slide is still on order so I worked the weekend on making some adapters and installing the PWK.  

For the engine side adapter, I used a thin rubber piece that made this connection perfect. For the air boot side, I found 2 different rubber sleeves at Home Depot to modify for this adapter. The one that seemed to work best is in the picture attached. I cut the ID slightly to make a nice slip fit over the carb and air boot. I have a hose clamp for this but not pictured. I will further modify the air boot connection and probably glue this piece together. The carb is nice and secure and installs and removes easily.

I also got a build your own throttle cable that I built for this carb. It came with several different ends and was cut to fit, I had to soldier one fitting on and a few other mods to make it work. I did build it to work with the OEM slider and I like that well.

I figured I would do some testing with the included needles and jets until the 2.0 slide comes in. The OKO has 3.0 slide and the tall needle jet holder so I wasn't expecting much. The first needle I tested was JJH and I didn't get good results. Mid-Atlantic included an additional needle which I think was N80F but not positive. The first attempt was close, and after a MJ change and clip position change it worked amazingly well. Throttle roll on from idle to WFO was smooth, no backfiring, no stumbling, and wow, way more responsive than the OEM carb.  I still have the 2.0 slide and other parts coming, so if that combination is better than what I have now I will be really happy. 

 

 

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I've had similar jetting issues with a PWK28 on my XR218 with the jetting recommended in this forum, I think the problem is the cam in my Powrolll 218 engine  has very aggressive lift rates and timing slightly longer than the XR, which is much more aggressive than a 230 cam. The result is reversion during overlap that richens the mixture.  I removed the baffle from the muffler and that leaned the lower end a bunch.
So your results with a leaner slide and larger pilot intrigued me as a possible solution.

Please verify the "N80F" needle as I've used other Keihin multi taper needles with good results on PD carbs (same needle family) but I  can't find that number on the Keihin web siite. 

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Chuck, go to the PWK discussion thread in this forum. On the last page I listed the details of this setup. That is the correct needle I listed. Someone gave the details on it, and it is available through mid-Atlantic as I verified this with Roger. I think it has a richer taper than the others I have tried. Also, 1gr8bldr noted that he used a bigger pilot than others have suggested, which is where I ended up

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